Garrett Stanley: Precise Timing in the Neural Population Code
Talk by Garrett Stanley, Coulter Dept. of Biomedical Engineering, Georgia Tech & Emory University. Given on April 29, 2009 to the Redwood Center for Theoretical Neuroscience at UC Berkeley.
The timing of action potentials relative to sensory stimuli can be precise down to milliseconds in the visual system, even though the relevant timescales of natural vision are much slower. The existence of such precision contributes to a fundamental debate over the basis of the neural code and, specifically, what timescales are important for neural computation. Through population recordings in the LGN, we show that the temporal precision in the neural response changes relative to the timescale of the visual scene, and that a high degree of temporal precision is necessary to represent the more slowly varying natural scene. More recent analysis of population activity reveals that this precision is preserved across the ensemble, and that it is invariant to features of the stimulus such as contrast. Finally, we have recently shown that ensemble activity expresses a sharp tuning for direction of motion in the scene, beyond that predicted by conventional linear models. The ensemble activity can be used to decode motion direction and speed over short timescales on a single trial basis. Taken together, these findings suggest an important role for precise timing of the neural population response in the representation of the dynamic visual scene.